Cathi, what kind of ants? And did they bite the little one?
I would get rid of the heating pad if it is a human heating pad, it will burn the skin as this one is to little and to weak to move off the heat. Instead make up some rice heaters with old socks, minute rice and a microwave. Fill the socks half full of uncooked rice. Tie off the ends and nuke the tied sock for 30 seconds. This gives you about two hours of "safe heat." You need a special nipple to feed this wee one- if you have a walgreens near you, then generally carry it- it has an elongated nipple that goes further into the throat. I would also pouch this baby, if you have a chest hugging backpack, or you can make a pouch from an old pillow case and a cord. Fashion it much like you would a purse, turning down the open ends and tucking the cord underneath, then securing the cord with a quick running stitch. Position the pouch so it is close to your chest right over your heart, put soft bedding inside and place the baby inside as well. He will be comforted by your warmth of your body and your beating heart.
If you can't do this, then keep him in a nice warm place out of drafts and keep it dark and quiet. He will need to be fed every two hours 24 hours a day. I would also get some liquid vitamins from your vet to add to the KMR- do not feed him milk. You will have to stimulate him very gently or you may tear his vulnerable skin. If he has been bitten repeatedly, he could be quite anemic and ill and so he needs to watched carefully
Oh and check your PM's